National Dental Examining Board of Canada (NDEB) Practice Exam 2026 - Free NDEB Practice Questions and Study Guide

The interprismatic substance within enamel is considered to be the most resistant to the action of acid due to its unique structural composition. Enamel is made up of tightly packed enamel rods, which are the primary structural units, and the intervening interprismatic substance, which connects these rods and provides additional strength and stability.

This substance is composed of a dense arrangement of mineral crystals, primarily hydroxyapatite, which contributes to its toughness and resistance to demineralization when exposed to acidic environments, such as those created by bacterial metabolism of sugars. While enamel rods and prismless enamel also provide structural integrity, the interprismatic substance's specific mineral composition and orientation offer superior resistance to acid erosion, protecting the overall integrity of the enamel.

In contrast, enamel tufts are structural defects or areas of increased porosity, which can be more susceptible to acid attack. Understanding these distinctions allows for better insight into enamel's resilience and the importance of preserving its structure in dental health.